Abstract

In this paper, we present a decision tree model for evaluation of the next generation radiation portal technology (Advanced Spectroscopic Portals or ASPs) to scan containers entering the United States non-intrusively against nuclear or radiological weapons. Advanced Spectroscopic Portals are compared against the current designs of portal monitors (plastic scintillators or PVTs). We consider five alternative deployment strategies: 1) Exclusive deployment of ASPs replacing all the PVTs currently deployed at U.S. ports of entry, 2) Sequential deployment of ASPs with PVTs installing ASPs in all secondary and some primary inspections areas, 3) Sequential deployment of ASPs with PVTs installing APs in only secondary inspections areas, 4) Exclusive deployment of PVTs, 5) Stop deployment of new portal monitors and continue inspections with the current capacity. The baseline solution recommends a hybrid strategy that supports the deployment of new designs of portal monitors for secondary inspections and current designs of portal through ports of entry, the probability of successful detonation, detection probabilities and the extra deterrence that each alternative may provide. We also illustrate that the list of most significant parameters depends heavily on the dollar equivalent of overall consequences and the probability of attack attempt. For low probability and low consequence scenarios, false alarm related parameters are found to have more significance. Our extensive exploratory analysis shows that for most parametric combinations, continued deployment of portal monitors is recommended. Exclusive deployment of ASPs is optimal under high risk scenarios. However, we also show that if ASPs fail to improve detection capability, then extra benefits they offer in reducing false alarms may not justify their mass deployment.